The father, whose identity also has not yet been released, was able to escape but his son remained strapped into his seat belt and trapped under the water.

Onlookers rushed to the crash site and jumped in to release the boy from the wreck, and he was rushed to a local hospital. But he was pronounced dead by hospital staff and, while there has been no official word on the cause of death, he is believed to have drowned.

Witnesses said the aircraft was in a group of three seaplanes that were out flying together above and around Lake Goodwin.

Wheels down: The wheels of the plane can be clearly seen in the down position. Authorities say this could have made the plane unstable when landing on water

The other two planes landed safely on the lake, but the third got into trouble.

Police said the boy was following correct safety procedures while flying in the plane, using two seat belts to keep him in his seat.

Unfortunately, it was this safety precaution that contributed to him being trapped underwater.

Witnesses said they saw the plane swiftly lose control as it landed on the lake.

Picturesque: Witnesses say three seaplanes were flying together over the beautiful Lake Goodwin, and the tragedy happened when the last one came in to land

KomoNews.com quoted Randall Smith as saying: 'It was just behind the trees from where we were at. We heard the pop and walked around and saw the plane was upside down.'

He said he called 911 and then got into a boat and headed out to the crash site.

He said he immediately jumped into the water with a knife and was able to cut through one of the boy's seat belts.

But he said he couldn't find the second safety belt in murky water.

Emergency divers were the next on the scene and were able to free the boy.